[PATCH][AArch64] Fix extern protected data handling

[Nick Clifton]

Hi Szabolcs,

> bfd/ChangeLog:
>
> 2015-07-22  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>
> 	PR ld/18705
> 	* elfnn-aarch64.c (elf_backend_extern_protected_data): Define.
>
> ld/testsuite/ChangeLog:
>
> 2015-07-22  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>
> 	PR ld/18705
> 	ld-aarch64/protected-data.d: New.
> 	ld-aarch64/protected-data.s: New.
> 	ld-aarch64/aarch64-elf.exp: Add new test.

Approved - please apply.

Cheers
   Nick